The research presented in this thesis is on the application of the injection-locked oscillator
technique to microwave balanced oscillators. The balanced oscillator design is primarily
analysed using the extended resonance technique. A transmission line is connected
between the two active devices, so that the active device resonate each other. The
electrical length of the transmission line is also analysed for the balanced oscillation
condition.
The balanced oscillator can be viewed with the negative resistance model and the
feedback model. The former model is characterised at a circuit plane where the feedback
network is cut. By using both the negative-resistance oscillator model and the feedback
model, the locking range of the oscillator is analysed by extending Kurokawa's theory.
This analysis demonstrates the locking range of the injection phenomenon, where the
injection frequency is either close to the free-running frequency, close to (lin) x freerunning
frequency or close to n x the free-running frequency. It also reveals the effect of
different injection power levels on the locking range. Injection-locked balanced
oscillators for subharmonic and fundamental modes are constructed. When the balanced
oscillator is in the locking state, it is clearly shown that the output signal is better
stabilised and the phase noise is attenuated. The experimental results agree with the
analysis. Furthermore, the spurious signal suppression in a cascaded oscillator is
investigated.
The other focus of this research is on the design of frequency doublers. A balanced
douber is designed and integrated with a balanced injection-locked oscillator. The
experimental result shows that the output signal is clean and stabilised. The other
important frequency doubler design technique studied is the use of the feedforward
technique to significantly eliminate the fundamental frequency component. The design
and the experiment show that the fundamental component can be suppressed to better
than 50 dBc.